#include "timer.h"
#include "led.h"
#include "usart.h"



//TIM3 PWM部分初始化 
//PWM输出初始化
//arr：自动重装值
//psc：时钟预分频数
void TIM3_PWM_Init(u16 arr, u16 psc)
{  
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
	TIM_OCInitTypeDef  TIM_OCInitStructure;
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);	//使能定时器3时钟
 	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB  | RCC_APB2Periph_AFIO, ENABLE);  //使能GPIO外设和AFIO复用功能模块时钟
	
	GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE); 	//Timer3部分重映射  TIM3_CH2->PB5    
 
   //设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形	GPIOB.5
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; 			//TIM_CH2
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  	//复用推挽输出
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB, &GPIO_InitStructure);				//初始化GPIO
 
   //初始化TIM3
	TIM_TimeBaseStructure.TIM_Period = arr; 			//设置在下一个更新事件装入活动的自动重装载寄存器周期的值
	TIM_TimeBaseStructure.TIM_Prescaler =psc; 			//设置用来作为TIMx时钟频率除数的预分频值 
	TIM_TimeBaseStructure.TIM_ClockDivision = 0; 		//设置时钟分割:TDTS = Tck_tim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); 	//根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
	
	//初始化TIM3 Channel2 PWM模式	 
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; 				//选择定时器模式:TIM脉冲宽度调制模式2
 	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 	//比较输出使能
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 		//输出极性:TIM输出比较极性高
	TIM_OC2Init(TIM3, &TIM_OCInitStructure);  						//根据T指定的参数初始化外设TIM3 OC2

	TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);  //使能TIM3在CCR2上的预装载寄存器
 
	TIM_Cmd(TIM3, ENABLE);  //使能TIM3

}
